1. Field of Inventions
The present inventions relate generally to refrigerated enclosures such as refrigerated display cases and storage units.
2. Description of the Related Art
One type of refrigerated enclosure is a refrigerated display case, such as those commonly found in grocery stores, convenience stores and florist shops. The term "refrigerated" is used herein to refer both to refrigerators at temperatures above freezing and to freezers at temperatures below freezing. Refrigerated display cases are used to display products that must be stored at relatively low temperatures and often include shelves, glass doors and/or glass walls to permit viewing of the products supported by the shelves. Refrigerated storage units, another type of refrigerated enclosure, are commonly found in warehouses, restaurants and lounges. They may also include shelves and are used to store food, beverages and other items stored at relatively low temperatures. Refrigerated display cases and storage units may be free standing units or "built in" units that form an actual part of the building in which they are located.
Whether free standing or built in, the refrigerated enclosures typically include a frame that supports one or more doors. The frames, which essentially define the forward portion of the surrounding enclosure, include top, bottom and side members and, in those instances where the frame supports more than one door, one or more vertically extending mullions. The frames also include plastic insulation that covers the rearward facing portion of the frame (i.e. the portion of the frame which faces into the cold storage area of the enclosure) as well as the outwardly facing portions of the top, bottom and sides of the frame.
There are a number of electrical components associated with the frame. For example, resistive wire heating elements are located in the enclosure perimeter frame members, the mullion and often the doors in order to prevent the condensation of moisture on the frame and doors. Typically, there is one heating element for the perimeter frame members and one for each mullion. Lighting fixtures, which typically include electric lamps, lenses and reflectors, are commonly secured to the rearward facing portion of the frame, which defines the forward portion of the enclosure. Light from the fixtures is directed rearwardly to illuminate the products within the enclosure.
In conventional frames, power transmission (or "power supply") wiring for the various electrical components is located within a raceway that extends along the rearward facing portion of the frame. Some conventional rearward facing raceways consist of U-shaped channels which are fastened to the rearward side of the enclosure frame over the plastic insulation. Such a raceway is disclosed in U.S. Pat. No. 3,499,245. In another conventional rearward facing raceway, a portion of the raceway is integral with the plastic insulation on the rearward facing portion of the frame. A separate cover is used to complete this variety of raceway.
The power transmission wiring is connected to the electrical components by extending lead wires from each electrical component through holes in the frame that lead into the raceway. Once a wire (or plurality of wires) is fed through the hole, the space between the lead wire and the perimeter of the hole must be filled with a plug, grommet or small amount of putty to prevent icing (which can occur when the cold air from within the cold storage area meets warm, moist air from outside the enclosure) and/or wire damage. With respect to the heating elements, the use of lead wires in this manner requires two connectors to be crimped onto each lead wire, one to connect the heating element to the lead wire, and one to connect the lead wire to the power transmission wire.
Moreover, two lead wires are required for each heating element, one for the "hot" connection and one for the "neutral" connection.
The inventor herein has determined that the process of connecting the power transmission wiring located within the rearward raceway to the electrical components is unnecessarily time consuming, labor intensive and expensive.
For example, installation of the electrical components in a conventional frame requires the entire frame to be flipped over four times, which is quite difficult because the frame is heavy and awkward. In a two-door (i.e. single mullion) arrangement for example, once the top, bottom and side frame members are welded together, the mullion (with lighting ballasts secured to the forward facing side thereof) is riveted or otherwise secured to the top and bottom frame members and the plastic insulation and integral raceway are secured to the rearward facing portion of the frame members. The frame is then flipped over a first time such that the raceway is facing down. The heating elements are then secured within channels in the frame. The lead wires from the heating elements are fed through holes in the frame into the raceway. This process involves crimping a connector onto the heating element, crimping one end of a lead wire to the connector and passing the lead wire through a small hole in the frame. The power input wires for the hinge pin sockets are also fed through holes in the frame into the rearward facing raceway. Grommets are then inserted into the holes. Next, the frame is flipped over a second time such that the raceway is facing up. The heating element circuits are then completed, as are the hinge pin socket power input wires. To complete the circuits, connectors are crimped onto the ends of each of the heating element lead wires and hinge pin socket power input wires in the rearward facing raceway. Many power transmission wires are then placed into the raceway. One "hot" and one "neutral" power transmission wire are used for the heating elements, while one "hot," one "neutral" and one "ground" power transmission wire are used for the hinge pin sockets. Connectors are used to connect the lead wires to power transmission wires. The time consuming conventional process of crimping the connectors onto the power transmission wires is discussed in detail below. The power transmission wires for the lighting circuit are placed into the raceway and then fed into the mullion, where the ballasts are located, through either the open end of the mullion or through a suitably placed punched hole in the mullion. The frame is then flipped over a third time such that the raceway is facing down and the forward facing side of the mullion is visible with the ballast exposed The power transmission wires are connected to the input side of the ballast. Additional power transmission wires are connected to the output side of the ballasts. Some of the power transmission wires from the output side of the ballast are connected to the lamp sockets on the rearward facing side of the mullion. This can be accomplished because in some conventional frames, the mullion includes holes that are aligned with the portions of the lamp sockets into which the power transmission wires are inserted. The other power transmission wires from the output side of the ballast, i.e. those which are associated with lamps on the rearward facing portion of the side frame members, are then threaded into the raceway through a grommeted hole. Next, contact plates are placed over the mullion and perimeter of the frame. The contact plates are secured in place with a zipper strip. The frame is then flipped over a fourth time such that the raceway is facing up. The wires from the output side of the ballasts are then run through the raceway to the sockets associated with the lamps on the side frame members. The sockets are secured to respective vertically extending plastic lamp support assemblies that are used to cover the rearward facing raceways on the vertically extending side frame members. Finally, once the lamp support assemblies are in place, covers are secured over the horizontal rearward facing raceways on the top and bottom frame members.
As alluded to above, other disadvantages associated with conventional rearward facing raceway frames are related to the multitude of crimped-on connectors that are used to connect the electrical components to the power transmission wires. For example, the above-described conventional two-door frame requires two heating elements and three hinge pin connectors (two singles and a double). Connection of the heating elements to the power transmission wires requires the use of eight crimp-on connectors, two to connect each heating element to the "hot" power transmission wire and two to connect each heating element to the "neutral" power transmission wire. The single hinge pin connectors require three crimp-on connectors each for the "hot," "neutral" and "ground" power transmission wires, while the double connector requires six. The crimping process time consuming and expensive.
Is also difficult to service refrigerated enclosures having conventional rearward facing raceway frames. For example, the large number of wires and phalanx of connectors makes it very difficult to traces wires to and from the electrical component to which they are connected. In addition, much of the power transmission wiring is separated from the associated electrical components by a frame member, which also makes it difficult to trace wires to a particular component.
The use of conventional rearward facing raceways also increases the thickness of the frame which, in many instances, is undesirable because of space constraints.